This application claims the priority of German Application No. 100 29 645.9, filed Jun. 15, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method for addressing components of a network, especially in the case of data bus systems in transport means, in which each component is assigned a first address for the mutual communication within the network and the first addresses are stored in a central register.
Today, electronic components in transport means, for example aircraft, ships, trains or motor vehicles, are no longer connected to one another via a multiplicity of individual cable strands which are combined to form cable trees or harnesses, but via one or more networks. Such networks use a data bus in transport means that can consist of metal conductors connected to the components in the form of a ring or in the form of a star, or of optical fiber or transparent plastic data bus lines in the case of an optical data bus.
The addressing of the individual components is a central subject in connection with vehicle data buses. Since many variants are possible in the production of the vehicle, this also entails a different configuration of the data bus and its components. Thus, individual components can be omitted or also provided several times. To ensure that each individual component of the data bus is known for the data traffic, and in order to be able to address each component in a defined manner, an address is issued for each component.
German Patent document DE 198 27 337 A1 shows a data bus which is preferably used in entertainment electronics. This concerns a time-synchronous data transmission in which the data transmitted are synchronized by using a code word at the beginning of each data frame. The address is transmitted together with the data to be transmitted via the data line. However, the addressing must be re-issued every time the system is reconfigured.
In U.S. Pat. No. 5,732,074, a wireless communication between a CAN data bus installed in a motor vehicle and a control processor connected to the Internet is disclosed. The control processor can be addressed via the Internet Protocol addressing (IP Addr) normally used in the Internet. A component provided at the CAN data bus is assigned such an IP address so that it can be addressed from the Internet. Within the CAN data bus, however, the individual components are not addressed with a network or device address designating the components but with the identifier normally used in the CAN protocol which allocates a particular priority to each message. Thus, no address is issued for the destination component in the CAN, but the message itself is identified via the identifier and can thus be distinguished from the other messages. In principle, each of the messages is then received by each component, the components then selecting the individual messages on the basis of the identifier. In this arrangement, each component must contain a listing of which message having which identifier is to be received. In CAN, the messages are thus not concatinated with addresses which describe a certain destination component at the data bus, but with identifiers which designate a certain message. The CAN data bus does not have any addressing in the sense that destination addresses are issued.
German Patent document DE 40 37 143 A1 shows a control system with a central control device and a number of components which are networked together by means of a data bus for mutual communication. After the system has been switched on, each component determines its logical device address via an established method. Mutual addressing takes place via a data line of the data bus. If the entire system is switched on, for example via the ignition key, the components are supplied with power and each component determines its logical device address. The address issued by a component is transmitted together with the message in order to correlate the message with the selected component. The configuration of the overall system can be stored in a central control device and/or the individual components, independently of the operating voltage, and only needs to be newly interrogated and/or stored when it is first taken into operation and/or when a component is exchanged.
It is then the object of the present invention to develop the method initially mentioned in such a manner that differentiated addressing of the components can be performed, especially in the case of complex networks. In this arrangement, selected components should also be addressable in a simplified manner by another network, for example the Internet.
According to the invention, this object is achieved by providing that at least one particular component of the first network communicates with another network, that this component, when dialling into the second network, is assigned a second address by the latter and that, within the first network, addressing takes place on the basis of function-specific address components, identical function blocks of the components being addressed via identical function-specific address components.
According to the invention, it has been found that, in the case of complex data bus systems in transport means, the addressing of the individual components can be decisively improved if addressing takes place via a function-specific component of the address. The starting point for the invention are data buses in motor vehicles in which, in contrast to the CAN protocol, each component on the data bus is assigned an address. The problem then is that, in the case of an exchange of the components or of a disturbance, the destination addresses can change. The advantage with a function-specific addressing is that a component can be addressed via its main function block and, when components are exchanged, the device address changes but not the function.
Using optical data buses as a basis, a first type of addressing which uses the function-specific address components is provided within the data bus in addition to the standard communication, for example D2B or MOST protocol. In addition, the first addresses can be set up in the manner of the Internet Protocol so that it is possible within the data bus to perform addressing virtually as in the Internet, a part of this address, however, being the function-specific component.
Independently of this addressing within the data bus according to the invention, one of the components on the data bus is provided for communicating with another network, for example the Internet. When the communication is set up, this component then receives a second address which is assigned to it by the Internet. The first address of the component is not visible to the Internet for security reasons. A component of a network can then be advantageously addressed from another network without the local address or position of the component in the first network having to be known in the other network.
According to the invention, the component for the communication with the other network has two addresses, namely the first address for the communication within the data bus and the second address of the second network. The component which is to be addressable from the second network, for example a communication component, allocates the addresses in accordance with the direction of communication to one or the other network.
The addressing in a network, for example the data bus, can take place, on the one hand, via an address component which describes the local arrangement of the components along the data bus such as can be the case, for example, in the D2B or MOST protocol and/or via a function-specific address component which describes the function of a component or its subordinate function blocks. Most of the components are constructed as control devices, the function blocks designating certain units such as, for example, an amplifier or a unit which controls the car telephone. Each function block can consist of hardware and associated software.
The special feature of the method according to the invention then consists in that each component of the one network which is to be addressed is addressed via the function-specific address component of a function block. As a result, for example, the control device for the Internet communication or satellite navigation can be addressed within the data bus by using the function-specific address for the function group Internet communication or satellite navigation, respectively.
In this arrangement, two aspects are particularly advantageous. The first aspect consists in that the first address uses the function-specific address component for addressing a component in the first network. As a result, only the IP address of the component to be addressed and the desired function of the destination component, and not the location at which a component or function group is precisely arranged, needs to be known in the case of activation from another network, for example the Internet.
The second advantageous aspect consists in that a component of the first network is addressed via its main function block. As a result, an address related to the local arrangement can be avoided. In consequence, the first address does not change in the case of a reconfiguration in the first network as long as the main function block remains linked to the component. The addressing should support the supply of a number of similar components in different function groups with data even in the case of an exchange of individual components, for example during a maintenance process of the vehicle electronics. The main function block is preferably the function block characteristic of a component.
The first network is addressed from the second network, for example the Internet. In this event, only the component having an assigned second address, for example an Internet Protocol address is visible. This second address can be dynamically issued, for example by an Internet Provider, i.e. the component is assigned an address by the Internet when the connection is set up.
In a preferred further development of the invention, the Internet Protocol addressing is mapped to the first network. As a result, the components in the first network can also be addressed via the Internet Protocol addressing in addition to the usual standard addressing for the first network. During communication with the second network, the internal virtual IP addressing of the first network is then translated to the external IP addressing with which the Internet can be addressed within the communication component. As a result, the Internet Protocol can be used in the first network after the translation in the corresponding component communicating with the Internet. In consequence, for example, Internet applications, software and also Internet browsers can address the components of the first network and use their information. The internal addresses of the first network are issued by the network master by dummy characters in the central register and are established when the system is started.
When the system is powered up, especially when the motor vehicle is started, first addresses are successively loaded into a central register of a component. The component having the central register is designated as network master. Firstly, the logical address of a component adjacent to the network master at the network is stored in the central register. The next logical address which is stored in the central register is the component which locally follows with reference to the network. In this manner, the logical addresses of the components are successively stored in such a manner that the network node at which a component is arranged at the data bus is known on the basis of this logical address. As a result, the individual components can be addressed via the logical address component of the first addresses. The network components can advantageously evaluate the first addresses stored in the central register in order to check the configuration of the entire system.
In addition to the logical addressing of the components/devices, the functional addressing is also provided. In this addressing, the components are subdivided into function blocks. In this manner, each function block can be addressed via the function-specific address component independently of the logical address of the component to which the function block is allocated. If a function block exists a number of times in the system, an additional identification address component is provided. If a function group exists a number of times in the system, it will be addressed via the function-specific component and via the identification address component during the function addressing.
As a result, the control devices, electrical circuits or the function blocks can be addressed via the data bus, and thus the data interface of the relevant control device, as an alternative to or in combination with the logical addressing via the function addressing. It can then be provided that the network node at which a component is arranged is addressed via the logical addressing and the relevant function block at the data bus is addressed via the function-specific address component.
In a further development of the present invention, a further address component of the address is issued by the network master, from which one of various similar components is unambiguously determined. This so-called identification address component is preferably a code word, for example a natural number, which in each case identifies identical or similar function blocks of one or more components in ascending order for mutual differentiation. The number xe2x80x9c0xe2x80x9d is issued to a function group, for example, if the latter occurs only once in the entire system. The next higher number is issued, for example, to the next function block registering with the central component if there is a number of these function blocks in the system.
When the system is powered up for the first time, the addresses relating to a component are copied by the network master via the data bus and stored in the interrogating component in the decentralized memory. A system according to the present description preferably consists of a network master which receives the addresses of all components on reconfiguration or on power-up of the system, and other components which only store the addresses of other components which relate to themselves in each case. The network master preferably has a central register in the memory area into which the addresses of all components are transferred. This transfer occurs during the system power-up by transmission of the addresses from the individual components to the network master or possibly from an external computer via an interface to the data bus and then to the network master or directly from the computer via an interface to the network master.
In the case of a reconfiguration of the system, the addresses copied by the centralized component via the data bus are stored in a decentralized memory of the relevant component. Whenever the system is taken into operation, that is to say after the operating voltages have been applied or when the vehicle starts, all components interrogate the network master for the addresses relating to them. When the system is newly assembled or, in the case of a reconfiguration, the addresses are copied by the network master via the data bus and stored in the decentralized registers in the memory of the other components. If the centrally stored addresses of the components differ from the addresses in the central register of the network master, for example in the case of a new start of a vehicle, the corresponding addresses are newly determined and copied via the data bus.
In a second further development of the invention, the coding rule of the IP addresses is only known to a centralized component, especially the network master. If IP communication is to be possible, the other components must interrogate the centralized component for this IP address. To prevent misuse, the main function block is also transmitted from the interrogating component to the centralized component, according to the invention, during the interrogation. In the centralized component, a configuration list is stored in which the main function block is entered which is assigned an Intranet or local IP address. This IP address is formed from the individual address components, especially the main function block and the other address components provided for the interrogating component in the list of the network master during the first power-up of the system. The centralized component checks the main function block of the interrogating component by means of the central list and, if the interrogating component is authorized, assigns to it the corresponding IP address. Finally, the assigned IP address is transmitted back to the interrogating component.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.